Sound amplifier



T. YOUNG SOUND AMPLIFIER Filed Dec. 24, 1925 2 Sheets-Sheet 1 Vf/V7.0@ noms You/va f I y D@n 4, 192s. 1,693,771

T. YOUNG sommo Aurm'ign' Filed Dec. 24, 1.925 2 Sheets-Sheet 2 WUMS 'Youu AWWEY Patented Dec. 4, 1928.

PATENT OFFLCE..

THOMASYOUNG, or ENrnitn ENGLAND.

SOUND AMPLIEIER.

Application filed December 24, 1925, serial No This invention relates toirrrprovements in sound amplifiers oftrumpetshape.

Broadly, my invention relates to sound am` plifiers oftrumpetshape, Whichxmay be used in apparatus tor the emission and ior the reception oit sound. For thek purpose of this specification, a ,trurnpet may he defined as a' tube whose bore gradually increases from one end to the-other,'and Whose axis may be either straight or Vcurved in any et theiorlns well knownhin connection with Windmusical instruments.

i Ther object of the invention is the provision of an improved 'ampliier vfor amplifying A'soundsemitted' by gra'mophenes, radio loud speakers, and the lik'e,or the provision of an im roved sound receiver for use in telephony eit ier by cable 0r Wireless, whereby the tone quality' of the original sound shall be preserved.

- Thev invention consists in a sound amplifier comprising a plurality of frusta ot' hollow conesin'adelof laminated wood, joined together preferably in such manner as to en- `sure as tareasy possible continuity in directionof the grain of the woody from venfdto end of the trumpet. K

The invention further consists" ina sound a'n'iplifier as defined in the precedingparagraph in which the various frustaare each nia-de by overlapping Winding or ceiling and gluing or otherwise fastening together' a plurality of flat strips'of wood oill suitable length and shape. l e

The invention further consists in a sound amplifierfas vllefinedv in' thc twov preceding paragraphs' in which the :frusta at a bend ,ot the trumpet are rstfmade all integral with the contiguous straight conicalpart or lparts ot the trumpet. are cut tl-ieret'ro'm,` andfy the whole ot' the parts are then joined togetl'ier.

The invention also consists in a sound amplifier as definedl inthe'preceding paragraphs. comprising al plurality of parts rotatably r joined togctheigthe axis ot joint being coincident or tangential to the axis of the trumpet at that place. By the use of lsuch joints the flare or mouth of a trumpet or horn may be set in any desired direction which may be chosen'l asA that best 'adapted to receive or 77,559,` and in Great Britain December ao; 1.924 Y part a right angle bend, andtheother part the tone-arm proper, the said tivo parts being rotatably jointed together, andthe other end ot the bend' being rotatably: jointed yto the cabinet or otherr part in fixed relation to the table ('ii'cabinetiot the gramophonc. Further, the tone-arm and horn of a gramophone are made as one; continuous ytrumpet comprising parts rotatablyvjointedtogethen i v Drawingsy are appended illustrating a `few forms in which my invention may be carried intro effect.

.Figures l and 2 diagrammatically illustrate my invention appliedto the tone arm and horn of a gramophone, Figure l being an elevation and` Figure 2a plan. i

Figures 3-5 are views Lshowing they details of thejoints of a jointed trumpet or horn.

liligures"` (-S are diagrams illustrating one method of making the parts of a trumpet.k

Figure 9 is a view. ofi a spiral or snail trumpet with a continuous surface which can be approximated to byv means of myV invention 'by' using a fairly largenumber of frusta per complete turn of the. spiral. y 4

In Figure. l vis shown a horn comprising a conical stem A1, a bendv made up of 'conical frusta B1, B2, B3, B4, a conical partA2 and 1 a conical mouth or flare C'.y `In one method,

the parts A1, B1, B2, B3, B4 and A2 are cut Y trema straight conical tube 'A as shown in elevation in Figure G,'by plane saw-cuts? oblique to the. axis i1-1 of the cone. It the two frusta divided by such a saw slit be reversed relative to eachother and. joined together they Will fit exactly. The axes .of the two frusta are now no longer in line but are inclined at an angle to each other, Where X is the angle whichy the normal to theiplan of thecut makes with the axis of the cone. For

a plain right angle bend as in FigureA 1, the f saw-cuts in Figure 6 are preferably all at'the same angle X, and oppositely incl-ined to the i axis of the cone. The four frusta necessitate 5 saw cuts, and as the axis 1--1,of theV bend Figure is bent` at an angle at each of the tive joints: the angle i is therefore 9 de- 'lhe Virusta VB1, B2, Bi", B are preterably all similar. rllhe axial length oit a frustum, beiney chosen to correspond with the desired mean radius ot curvature at the e.art cir the bend. that ot the others is determined by a well known geometrical method, such as by drawing;- Athe series of similar triann es indicated by thc dotted lines. rightfiangle bend may comprise any 1onrenient number lilith three frusta inyoly' e' tour joints the angle X is 1125 de- .'rees: with tro irulsta the angle K is 15 degrees. ne greater the nun ber ot Ytrusta the more i l es the axis of the bend aposcly e.

c c piofniy e to a. logarithmic spiral, and its inner a id outer surfaces approximate to continuous sin-tacos.

Theoretically,

w al' the width o'li the Saw-cn .s implies that contiguous e .l r 1, El. B3. llt ant. if when shown in Figure 1 do not Vx:Cecily it; but in practice, the saw-cuts are so thin that the deviation from perfect lit of the joints is practically negligible.

The said parts may ot course be each riode independently, their edges being` trimmed so as to secure exact tit when assembled. but this process ot manufacture is more tedious.

The bend and tone-arm 5 ot' a gramophone (Figures 1 an( Q) are made in the same manner as described with reference to the trunipet parts Dil, B1, Bg., B3, Bt, A2.

i Spiral or snail7 trumpet bend can be made in a somewhat similar manner as 'tollow The end A? oin the tube (Figo-re t5) bei ig held in a lathe, atter cutting' oil' the part A1, the tube Aia rotated through a enitable small angle be'orc cutting' ott the frustum B1: and so on. the tube being rotated after cuttingoli each trustum. Arsnail trumpet made with 21 segments per complete turn approximates 'fairly closely to a continuous surface trumpet. as in Figure t) which shows a continuous snail trumpet ot one and a quarter turns.

The tube A (Figure (i) is made iy coilin;l two or more. layers` o'l.I thin wood on a z drel. lllie'ure T Shown the development two layersA ffl and o3. Each layer may comprise two or more piel-es arranged as shown. The various pierce are eut so that their tout; cda' e when coiled round the mandria are inielined to the straight lines whi :h an bc drawn on the surface of the conical mandrel..

Figure 8 shows the development of the flare or mouth C ot the trumpet (Figure Each layer is shown as made up ot' six segments and the run ot' the ernia is indicated in two adjacent pieces ot the layer of. The greater the number ot segments the less is the break in continuity et direction olf the Agrain in passing from segment to segment.

The small end of the tube A and the ends eee-s ot the p a s in `lltigi'ure 3 are L ad'iped to form ball-races. Alor a ball bearing. lli Are irl a. section of the :tourt at 1t) between the bend et and tone arm Figure -,lis a .section ot the joint at 11 in which the iterrulc 7 attached to trumpet A* is .screwed in tired relationship to a base plate l2 which is fastened by screws or the te to the eji'aniophono cabinet or table T, the bend i being rotatal'ile relative to said plate. The trumpet is thus attached to the Vabinet only at its small bore end its mouth bein presented to the openinLT at the door D, but is not fixed there in any way. It is otherwise not constrained and free to yib 'ate without any camping action as is the case when additional support is provided.

Figure is a n'ioditication ot' the joint at 11, which permits the trumpet to be rotated relative to the base plate 12, in cases where the base or trame ot the instrument permits. These joints each comprise a double thrust ball-race 14a the assemblage being completed by an outer ball-race ring 15 screwed to the other outer ball race 1G. In Figure 5. an additional plain bearingr is provided, the ballrace 1G being rotatable relative to the base plate 12 and secured in position by a ring 17 screwed to the base plate. A springl washer 18 may be inserted between the base plate 12 and ball race 16. exerting pres-ture between the yarious parts ot the -ioint. The mouth C of the trumpet ri can be set in any desired direction horizontally, and the friction of the joint will tend to keep it in position, until appreciable ei/i'ortis exerted to change its position.

I find that sound amplifiers or trun'xpcts made oit wood according to my invention when applied in connection with gramophones` and loud Speakers for wireless telephony reproduce more Yfaithfully than has been the ease hitherto the essential characteri tics ot the original sound. Prol'lably this is due to the. `tact' that the. higher overtones. which constitute the equality or timbre peculiar to au individual voice. musical in:-` 'fument7 orchc-tra or choro. arc not moditicd or suppressed. while the trumpet does not introduce any new overtones duc to itsI own construction.

1 claim 1. A sound amplitier comprising a plu ality of laminated. wood. hollow conical frusta, having their base edges joined together. the wood `gra in ot the entire amplifier running in a direction sub-itantiallyv lengthwise ot the amplitier.

-i method of making a sound amplitier which consists in makinI a hollow coni :al tu ie of laminated wood, cutting said tube into several frusta, reversing certain frusta the tonearm proper is rotatably jointed to from their cut outposition, and securing tosaid neck and each comprise a plurality of gether the base edges of the several frusta laminated Wood hollow conical frusta. hav- 10 so that the axis of one frusta makes an angle ing their base edges cemented together. 5 vwith the axis of another frusta. In testimony whereof, I aix my signature.

3. A tone-arm for a gramophone in which the neck is rotatably jointed tothe casing and THOMAS YOUNG. 

